In the past 20 years, the progressive ability to grow blood forming cells in tissue culture, has dramatically increased our understanding of blood disorders and has allowed the isolation of many new hemopoietic hormones which may now be used for some of these disorders. Nevertheless, until recently, the hemopoietic cultures assays have been time consuming, expensive and labor intensive, and the hormone activities poorly standardized. Our proposal seeks to exploit recent advances in culture technology and recombinant hormone production to develop a rapid, pre- standardized assay kit that will permit clinical hematology laboratory personnel to routinely perform overnight cultures that assess the hormone-dependence of hemopoietic cells in patients with blood disorders. It is well known that many breast and prostate cancers are hormone-dependent and respond to anti- hormone therapy. On the basis of several animal and a few human studies, it is suspected that cancers of the blood, pancreas, thyroid, brain and other tissue may also remain hormone- dependent. The proposed kits will permit wide spread testing of hormone sensitivity in hematology oncology patients. The accumulation of such information may then lead to new hormone based approaches to the treatment of leukemia and other cancers. Furthermore, according to published animal studies, the assays should be useful for the early detection, diagnosis and therapeutic monitoring of leukemias.